I searched through the latest posts in the glacial spike thread, from 6 months ago, but didn’t feel satisfied that I had an answer to this question.

Currently when running glacial spike is it better to use ebonbolt on cooldown and fish for brain freeze procs before casting glacial spike, OR keep EB off CD for those moments when GS is ready with no BF proc?

Using Ebon on CD except when you have 4+ icicles is a very slight dps increase. Probably around ~0.3%.
It's not a big swing either way. If you prefer to have Ebon as backup, you could hold it and there wouldn't be too much difference.

I had a follow up question on this. I feel like my ebonbolt is practically worthless, because I'm holding it as a back-up for needed BF procs. If I'm doing this, wouldn't Frozen Touch just make more sense? It seems like with how rarely I don't have a BF on GS proc now, I would never have a problem if I was using frozen touch. Has anyone simmed all of this?

I just feel like Ebonbolt is klunky in my rotation and am curious if I'm using it right. I spend ~90% of my time in a M+ environment and the other 10% of time raiding. I'm most curious from a M+ perspective.

I am usually opening with flurry (see my latest post) and following up with troll berserk+orb, icy veins, frostbolt, drop FoF. If at this point I have a brain freeze I normally frostbolt + shatter it (that makes 4 icycles), then I use frostbolt followed by an ebonbolt to generate a new brain freeze to shatter the GS with.

But it is highly likely you get another brain freeze process with 2-3 icycles, in which case I normally shatter it and await some luck for the Glacial Spike... I don't usually need to wait more than a couple of frostbolts to get another BF.

While it is possible, and I have gone through, frustrating moments when you just don't get a brain freeze, I still prefer to use ebonbolt on CD when I have these 2-3 icycles followed by flurry+ice lance and pray for an early brain freeze proc for my next GS.

As you say, Frozen Touch is a perfectly valid option to Ebonbolt, yet I still like ebonbolt as it gives me more control on what I do. Let's say, take better advantage of certain azerite +dmg procs, boss debuffs (e.g. Motherlode 1st boss) more efficiently by shattering an ebonbolt which is still a decent dmg boost, even if that means slightly delaying my next GS. If the new GS comes as intended, I have not lost any dmg - rather on the contrary; but if it does not, anyway I can afford to wait a bit, as there is no significant buff/debuff I can benefit of...

So that's my two cents.

P.S: In a M+ environment I find ebonbolt even more useful, but only if you pair it with splitting ice.
Most of the pulls you don't have time to build up a GS, so ebonbolt gives you a minor boost to finish off a mob. Plus, you can freeze your target instead of using BF to shatter the GS, and even if you do not shatter the GS, it is still ok as you're most of the time hitting a second target with it.

A friend and i tested around this question two weeks ago. After several hours of hitting the dummys our answer to this problem ís, that holding ebonbolt for a glacialspike without brainfreeze procs makes the most sense.

We both had tested around with Frozen touch and found ourselfes to have way more casts (5-10) of Frostbolt while GC was up to fish for BF. same if u used ebonbolt on cd. U will just get to a Point where u will only cast frostbolts cause that shit just doesnt proc.

So in our opinion savin Ebonbolt for GC without the BFproc is the most satisfying thing to do.